chore(shell_command) fix freeform timeout output (#7791)

## Summary
Adding an additional integration test for timeout_ms

## Testing
- [x] these are tests

codex-rs/core/tests/suite/shell_command.rs

@@ -13,10 +13,15 @@ use core_test_support::test_codex::TestCodexHarness;
 use core_test_support::test_codex::test_codex;
 use serde_json::json;
 
-fn shell_responses(call_id: &str, command: &str, login: Option<bool>) -> Vec<String> {
+fn shell_responses_with_timeout(
+    call_id: &str,
+    command: &str,
+    login: Option<bool>,
+    timeout_ms: i64,
+) -> Vec<String> {
     let args = json!({
         "command": command,
-        "timeout_ms": 2_000,
+        "timeout_ms": timeout_ms,
         "login": login,
     });
 
@@ -36,6 +41,10 @@ fn shell_responses(call_id: &str, command: &str, login: Option<bool>) -> Vec<Str
     ]
 }
 
+fn shell_responses(call_id: &str, command: &str, login: Option<bool>) -> Vec<String> {
+    shell_responses_with_timeout(call_id, command, login, 2_000)
+}
+
 async fn shell_command_harness_with(
     configure: impl FnOnce(TestCodexBuilder) -> TestCodexBuilder,
 ) -> Result<TestCodexHarness> {
@@ -54,6 +63,20 @@ async fn mount_shell_responses(
     mount_sse_sequence(harness.server(), shell_responses(call_id, command, login)).await;
 }
 
+async fn mount_shell_responses_with_timeout(
+    harness: &TestCodexHarness,
+    call_id: &str,
+    command: &str,
+    login: Option<bool>,
+    timeout_ms: i64,
+) {
+    mount_sse_sequence(
+        harness.server(),
+        shell_responses_with_timeout(call_id, command, login, timeout_ms),
+    )
+    .await;
+}
+
 fn assert_shell_command_output(output: &str, expected: &str) -> Result<()> {
     let normalized_output = output
         .replace("\r\n", "\n")
@@ -172,3 +195,32 @@ async fn pipe_output_without_login() -> anyhow::Result<()> {
 
     Ok(())
 }
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn shell_command_times_out_with_timeout_ms() -> anyhow::Result<()> {
+    skip_if_no_network!(Ok(()));
+
+    let harness = shell_command_harness_with(|builder| builder.with_model("gpt-5.1")).await?;
+
+    let call_id = "shell-command-timeout";
+    let command = if cfg!(windows) {
+        "timeout /t 5"
+    } else {
+        "sleep 5"
+    };
+    mount_shell_responses_with_timeout(&harness, call_id, command, None, 200).await;
+    harness
+        .submit("run a long command with a short timeout")
+        .await?;
+
+    let output = harness.function_call_stdout(call_id).await;
+    let normalized_output = output
+        .replace("\r\n", "\n")
+        .replace('\r', "\n")
+        .trim_end_matches('\n')
+        .to_string();
+    let expected_pattern = r"(?s)^Exit code: 124\nWall time: [0-9]+(?:\.[0-9]+)? seconds\nOutput:\ncommand timed out after [0-9]+ milliseconds\n?$";
+    assert_regex_match(expected_pattern, &normalized_output);
+
+    Ok(())
+}